Note 5 - Inventories (Details Textual) - USD ($)	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Inventory Write-down	$ 28,000	$ 161,100
Inventory Valuation Reserves, Ending Balance	4,993,000		$ 4,965,000
Cable TV [Member]
Inventory Write-down	0	200,000
Inventory Valuation Reserves, Ending Balance	4,150,000		4,150,000
Telco [Member]
Inventory Valuation Reserves, Ending Balance	843,000		$ 815,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Increase (Decrease) Adjustment	30,000
Inventory, Lower of Cost or Market Reserve	$ 0	$ 12,000